fix: Don't round bits that will be milldrilled.

This fixes #631

drill.cpp

@@ -844,6 +844,11 @@ map<int, drillbit> ExcellonProcessor::optimize_bits() {
       auto& wanted_drill_bit = wanted_drill.second;
       auto old_string = drill_to_string(wanted_drill_bit);
       const Length& wanted_length = wanted_drill_bit.as_length();
+      if (min_milldrill_diameter &&
+          wanted_length.asInch(inputFactor) > min_milldrill_diameter->asInch(inputFactor)) {
+        // We're not going to drill this one anyway so don't adjust it.
+        continue;
+      }
       auto best_available_drill = std::min_element(
           available_drills.begin(), available_drills.end(),
           [&](AvailableDrill a, AvailableDrill b) {

testing/gerbv_example/milldrilldiatest_units/expected/drill.ngc

@@ -40,10 +40,6 @@ G81 R1.50000 Z-1.75000 F100.00000 X120.00000 Y-100.16000
 X120.00000 Y-97.62000
 X120.00000 Y-95.08000
 X130.16000 Y-90.00000
-X130.16000 Y-92.54000
-X130.16000 Y-95.08000
-X130.16000 Y-97.62000
-X130.16000 Y-100.16000
 G80
 
 G00 Z10.000 ( All done -- retract )

units.hpp

@@ -148,6 +148,9 @@ class UnitBase {
       throw comparison_exception("Can't compare with units and without.");
     }
   }
+  bool operator>(const UnitBase<dimension_t>& other) const {
+    return other < *this;
+  }
   bool operator>=(const UnitBase<dimension_t>& other) const {
     return !(*this < other);
   }